When using a socket wrench to install or remove a nut or bolt, there is a tendency for the nut or bolt to fall out of the socket when it is not engaged. When the nut or bolt is engaged, the retaining force on the nut or bolt is much greater than the holding force on the socket. Therefore, the wrenching tool, including the socket, can be retracted off of the nut or bolt.
Using a socket that holds the nut or bolt is useful in manual operation, but is particularly useful when the wrenching operation is automated, since there may not be an operator near the wrench to replace the nut or bolt if it falls from the socket.
Magnets have been used to hold a nut or bolt in a socket. However, there is a possibility that foreign, ferrous material may be attracted by the magnet and enter the socket, requiring an operator to remove the foreign material.
Thus, there is a need to provide a structure for holding a nut or bolt in a socket by friction or by a vacuum.